Pump by-pass

ABSTRACT

A fluid pump having a by-pass circuit comprising by-pass ports adjacent to the inlet and outlet zones of the pump, a flexible diaphragm and means biasing the diaphragm to close one or both of the by-pass ports and, thus, close off the by-pass circuit at least when the pump is at rest.

United States Patent 1191 FOREIGN PATENTS OR APPLICATIONS I Sweden .L; 417/310 [111 3,806,283 Leverett Apr. 23, 1974 [54] I PUMP BY-PASS 899,202 6/1962 Great Britain 417 310 [7 5] Inventor: Edward G. Leverett, Roydon, Harlow England Primary ExaminerCar1ton R. Croyle [73] Assignee: International Standard Electric Assistant ExaminerfRichal'd Shel Corporation, New York, NY, Attorney, Agent, or Firm-Thomas L. Peterson [22] Filed: Jan. 4, 1973 [21] Appl. N0.: 320,988 [57] ABSTRACT [52] US. Cl. 417/310, 417/283 A fluid pump having a by-pass circuit comprising b [51 Int. Cl. F041) 49/08 as ports adjacent to the inlet and outlet zones of the [58] Field of Search 417/310, 283, 31 1; pump, a flexible diaphragm and means biasing the di /154, 132 phragm to close one or both of the by-pass ports and, thus, close off the by-pass circuit at least when the [56] References Cited p mp is at rest. I

6 Claims, 5 Drawing Figures MIME-W23 m4 $1806; 283

SHEET 3 BF 3 1 PUMP BY-PASS I BACKGROUND OF THEIINVENTION 1. Field of the Invention This invention relates to afluid pump and, more particularly,to a by-pass circuit for such a pump.

2. Description of the Prior Art The device of the present invention may be used on many. forms of fluid pumps. However, the invention has been found to be especially advantageous when used with arubber impeller pump such as disclosed in any one of the following US. Pat. Nos; 2,782,723,

F or some applications, it is desired that there be provided a by-pass circuit'for a fluid pump. An example of such an application is when a pump is used to pump wine through filter paper. A by-passcircuit is desired in this instance to provide a cushioning effect which will minimize a shock wave that could take place in such an application and, thus, eliminate or at least minimize thedamage which might otherwise occur to "the filter paper.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial longitudinal sectional view through a fluid pump embodying the by-pass circuit of the present invention;

.FIG. 2is a front elevation of the pump housing wall embodying the by-pass ports;

FIG. 3 is a transverse sectional view taken along line 3 3 of FIG. 1; and FIGS. 4 and 5 show the performance characteristics of the pump of the present invention.

DESCRIPTION OF THE PREFERRED 1 EMBODIMENT Referring now to FIGS. 1-3 in detail, there is illustrated a fluid pump, generally indicated 10, which embodies the by-pass'circuit of the present invention. The pump includes a housing 12 providing a chamber 14 for a rubber impeller 16 having a hub 18 and radial vanes. 20 adapted to be flexed in the usual manner by a cam 22. The housing 12 consists of an intermediate ring section 24 closed at its opposite ends by plates 26 and 28. 1

Extending into the chamber 14 is a shaft 30 driven by any suitable means, such as a motor 32.

The end 34 of the shaft 30 in the chamber 14 is externally splined to engage internally splined bushing 36 to which the hub 18 of the rotor is sealed. A suitable shaft seal 40 prevents leakage of pump fluid along the pump shaft.

As best seen in FIG. 3, the pump housing 12 includes inlet and outlet ports 42 and 44, respectively. The areas 2 of thepump chamber 14 adjacent to ports 42 and 44 define inlet and outlet zones 46 and 48 therein.

The portion of the pump 10 described so far is generallyconventional and constitutes no part of the present invention, the latter being a by-pass circuit, generally designated 50. The by-pass circuit may be applied to any form of pump, the vane type pump described herein being given by way of example only. The by-pass circuit comprises an enclosure 52 secured to the end plate 26 of the pump by bolts, not shownjThe enclosure is formed with a recess 54 and vent passage 55. The plate 26 is formed with by-pass ports 56 and 58 which communicate with the pump chamber 14 adjacent the inlet andoutlet zones 46 and 48, respectively. It will be understood, however, that the ports 56 and 58 could be angularly offset from the respective angular positions of the inlet and outlet zones of the pump provided that in use by-pass flow will be established.

When the pump is at rest, the ports 56 and 58 are closed bya flexible rubber diaphragm 60. The outer re- .gion of the diaphragm is bonded by an adhesive to an annular recess 62 in the face of the enclosure 52. A circular thrust pad 64 is positioned adjacent to the diaphgram The pad carries an axially extending pin 66 which is surrounded by coil spring 68. The enclosure ably engaged on the boss 70. The knob 74 acts as a stop member for the end 76 of the pin 66 which extends through an aperture 78 in the end of the boss. A rod 80 is press fitted in a vertically extending passage 82 in the knob 74 to facilitate rotation thereof.

When the pump s'tarts,'fluid pressure in the pump chamber 14 will create a pressure on thepumpside of the diaphragm 60 but cannot move the diaphragm away from the endplate 26 of the pump housing because the pin 66 andthrust pad 64 hold the diaphragm against movement. When the knob. 74 is unscrewed slightly, the fluid pressure in pump chamber 14 will overcome theforce of the spring 68 to move the diaphragm'away from the plate 26 to form a by-pass chamber therebetween, and a by-pass flow will start, thus reducing the flow of liquid through the pump. The bypass flow can be adjusted by the knob 74.

Although not shown, it is conceivable that means can be provided for altering the compression force of the spring 68. M

It will be appreciated that the diaphragm 60 will close upon the bypass ports 56 and 58 when the pump is at rest. This enables the pump to be automatically selfpriming.

The by-pass circuit 50 could be arranged to act'as a safety device, by being arranged to come into action only in the event of undue pressure build-up in the pump. t

It is possible that thediaphragm will, when the control knob 74 is positioned to allow a by-pass flow, provide a cushioning effectwhich may minimize a shock wave which can take place in certain installations, for example, when the pump is used to pump wine through filter paper. The chance of damage which might other- 7 wise occur can thus be eliminated or at least minimized.

FIGS. 4 and 5 show performance curves of, respectively, a Jab sco-type 1 I640 pump and Jabsco-type 21000 pump, each fitted with-a by-pass circuit substantially as described herein. Such Jabsco pumps are manufactured by ITT Jabsco, Costa Mesa, California. In each figure, curve A represents the performance with the by-pass circuit closed. Curve B represents the performance with the diaphragm movement at a maximum, that is, full by-pass flow.

In a typical filtration system, it is important that pump characteristic is selected to suit the filter or filters being used. If pump flow is considerably in excess of the nominal filter capacity giving high fluid velocity, probably inadequate filtration and damaging of the filter elements may occur. Therefore, the pump flow should be reduced by throttling the inlet valve (not shown), or opening the by-pass 50 or a combination of these two techniques.

Although I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of my invention which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent structures and devices.

What is claimed is:

l. A fluid pump having a by-pass circuit comprising:

a pump housing having a chamber therein and inlet and outlet ports communicating with inlet and outlet zones, respectively, within said Chamber;

a pump member mounted for rotation in said cham her about an axis;

said housing including an end wall perpendicular to said axis; I

inlet and outlet by-pass ports extending through said end wall generally parallel to said axis, said by-pass circuit including said by-pass ports;

a flexible diaphragm in juxtaposition with the outer surface of said end wall and extending over said bypass ports; and

means biasing said diaphragm into engagement with said end wall to close said by-pass ports at least when the pump member is at rest.

2. A fluid pump as set forthin claim 1 wherein:

said housing includes a ring section surrounding said pump member; and

said inlet and outlet ports are provided on said ring section.

3. A pump as set forth in claim 1 including:

a thrust pad engaging the surface of said diaphragm opposite to said end. wall, said pad carrying a rigid projecting pin extending parallel to said axis;

said biasing means engaging said thrust pad; and

screw threaded means directly engaging the free end of said pin, said threaded means being movable, by screwing, to increase and decrease the limit of diaphragm movement.

4. A pump as set forth in claim 1 including:

by-pass flow adjustment means for controlling the flow of fluid through said by-pass ports.

5. A pump as set forth in claim 1 including:

an enclosure for said diaphragm attached to said housing; and

said diaphragm being sealed in a fluid-tight mannerv along its peripheral region to said enclosure.

6. A pump as set forth in claim 1 wherein:

and outlet zones. 

1. A fluid pump having a by-pass circuit comprising: a pump housing having a chamber therein and inlet and outlet ports communicating with inlet and outlet zones, respectively, within said chamber; a pump member mounted for rotation in said chamber about an axis; said housing including an end wall perpendicular to said axis; inlet and outlet by-pass ports extending through said end wall generally parallel to said axis, said by-pass circuit including said by-pass ports; a flexible diaphragm in juxtaposition with the outer surface of said end wall and extending over said by-pass ports; and means biasing said diaphragm into engagement with said end wall to close said by-pass ports at least when the pump member is at rest.
 2. A fluid pump as set forth in claim 1 wherein: said housing includes a ring section surrounding said pump member; and said inlet and outlet ports are provided on said ring section.
 3. A pump as set forth in claim 1 including: a thrust pad engaging the surface of said diaphragm opposite to said end wall, said pad carrying a rigid projecting pin extending parallel to said axis; said biasing means engaging said thrust pad; and screw threaded means directly engaging the free end of said pin, said threaded means being movable, by screwing, to increase and decrease the limit of diaphragm movement.
 4. A pump as set forth in claim 1 including: by-pass flow adjustment means for controlling the flow of fluid through said by-pass ports.
 5. A pump as set forth in claim 1 including: an enclosure for said diaphragm attached to said housing; and said diaphragm being sealed in a fluid-tight manner along its peripheral region to said enclosure.
 6. A pump as set forth in claim 1 wherein: said by-pass ports are located adjacent to said inlet and outlet zones. 